Chefs Note:i tried this with salmon (the 'steak of the ocean') and found it works marvelously.

This is a great way to cook fish, letting it retain all its natural juices and moisture and rewarding you with the most fantastic tasty sauce. I think the fish is best served in its bag in the middle of the table - it's real theatre. When the bag is broken open the fragrant smells waft all around the table, leaving everyone salivating for it.

MethodPreheat the oven to 220°C/425°F/gas 7. Tear off a piece of kitchen foil 5 times as long as your fish, then fold this in half to give you double thickness. In the middle of one half of the foil sprinkle the red onion, fennel and garlic. Place your fish snugly on top of the veg. Season the inside and outside of the fish with sea salt, freshly ground black pepper and the fennel seeds, then stuff with all your herbs - use just one herb or a mixture of your favourites. Squeeze over the juice of 2 of the lemons, slice the third lemon and tuck around the fish, and pour over the olive oil.

Fold the foil over the fish and seal the three edges neatly and tightly, being careful not to pierce the foil as this will let the juices escape. Cook in the preheated oven for 10 minutes per 455g/1lb. If using a 1.8kg/4lb fish, then obviously give it 40 minutes, if using 2 two-pounders (900g) then you only need to cook them for 20 minutes. Once removed from the oven, allow the fish to rest for 5 minutes before serving at the table. Nice with simple boiled potatoes and a crisp salad.